Why 2 dc Inputs on inverter ??

[madmaz]

Hi,

Why are there 2 inputs on my inverter when i only have 1 mppt, the installers have doubled up (in parallel) the 2 strings in the dc isolator and wired 1 set of leads from that to 1 input, should they have used both inputs ??

Not convinced by these guys at all !!!

Many Thanks

 

[bumcrack]

It is probably to keep individual string voltages within inverter limits. What size system is it?

 

[Somecamel]

Nothing wrong with using 2 different DC inputs, as 'bumcrack' above states. Anything less than a 2kW and I would start to wonder though

 

[madmaz]

thanks for replys its a 3.64kw system with 2 strings of 7 panels, just wondering why itsnot wired to the two inputs on the inverter as i have 4 wires going to roof an 2 out of dc isolator should there not be 4 ?

thanks

 

[Markc]

Depending on the make and model of inverter some are commoned inputs 1 & 2. Meaning even if each input was used the overall connection would be the same as a single connection.

 

[madmaz]

solar river inverter ?

 

[Markc]

solar river inverter ?

Never heard of it. Sorry

 

[madmaz]

so its ok to wire like that and not as 4 wires into inverter it says its mppt is 1/2 ?

sorry about this inverter max current is 17A and max voltage is 500V each string is 414.4V and 5.87A according to paperwork

 

[SolarCity]

I don't know what inverter you have but the figures look ok. They will have needed to wire the system like that so that your voltage doesn't exceed the maximum of the inverter.

I think it is good practice to have a DC isolator for each string though.

 

[JulianC]

I think madmaz's query relates to why both strings are plumbed into one isolator then into one input of the inverter, rather than into 2 isolators and into both inputs of the inverter. I'd say it was down to penny pinching or laziness. Nothing intrinsically wrong with doing it this way, providing the isolator and outgoing cable is sufficiently rated (most likely is) but I would prefer to see each string into its own isolator.

 

[dansk]

It would have been better to use branch connecters on the roof and then brought two wires into iso.

 

[Maff]

Maybe they couldnt get hold of any branch connectors until after the 8th?